After using Hartz 2-1 flea and Tick Shampoo

Last Sunday I gave both of my dogs a bath in this shampoo-I have a 100 lb. Aussie mix and a small 20 lb chihuahua/minpin mix-the bigger dog seems fine but the day after bathing my smaller dog in this shampoo-(nothing else had changed for him during this time) he started vomiting and having diahrrea-he would not drink or eat and was just all around sick. I called the Hartz company and they actually gave me a case# and told me to tell the vet to call them if any questions- however my vet (whom I noticed has Hartz products on display) told me she didn’t think the shampoo had anything to do with his illness-she labeled it gastroenteritis and gave him two injections one for nausea and one for stomach acid-and also administered subcutaneous fluids. Before I left the office my dog had diahrrea on the floor it was a hugh puddle of blood! The vet then said that I may have to have him hospitalized if he had any more bloody diahrrea-calling it hemorrhagic gastroenteritis. I ask what could cause this and she said the cause is unknown or maybe I had fed him some fat and that could cause these symptoms. I took him home and as of today he does seem to be getting better but his right hind leg now shakes uncontrollably. I will never use this product or any of the Hartz products again. I had cats in the past that also got sick from the flea and tick drops.